Anyone of you fellows have any pictures ref to cutting a frame to shorten the wheel base ? As some of you all know my Grandson and I are putting a 38 chevy cab on a 51 Chevy 1/2 ton truck frame and want to make it somewhat of a "Bobber" type truck. Have fun and thanks to all.
The '51 1/2-ton frame tapers from front to about the rear axle, meaning you'll be changing the spring mounts and maybe the taper if you shorten that frame.
No pictures, but; 1. Pick a straight run about a foot and a half ahead of the rear spring front mount. Mark both sides. 2. Support it. Whack it. 3. lap and clamp it. Check for alignment. 4. I would bolt the lap joints. Some people would weld and add gussets to strengthen.
1 How much shorter? 2 have you set the cab position? might want to do that first. 3 if you cut the frame through any mid section make sure you fish plate the inside weld area for strength along with welding the outside. 4 make sure you both have a tape measure and a lot of clamps to square the frame, constantly checking everything. Front to back, cross measurements, and side to side. I have done quite a few custom frame styles. And everyone is a little bit different. Good luck...John
Thanks Guys. We were thinking of cutting about a foot . Have read some cut the frame at a 45 degree angle and some say straight.I saw this cutting done on some truck show on TV in the past to turn a long bed into a short bed but at my age I,m doing good to remember yesterday !!!! LOL
By cutting the frame on a 45 deg. angle istead of a verticle cut, you get about 50% more weld area (length). For a study in the proper way to fishplate, go look at construction machinery. Such as a backhoe/loader or a front load refuse truck that picks up the big metal containers & dumps them. Both of these examples have fabricated arms that take a lot of repeated stress & are designed by experienced professionals. Study the size, shape, & orientation of their fishplates. Repeat this on yours. Welding process used is another story. But, to start with, I'd use the cut out section to make the fishplates with. NOT some foreign made cold rolled from a iron yard. Need more, buy a frame section from a junkyard truck.
My grandfather and I usedto shorten or lengthen frames .He's gon now but I still remember how to do it. We cut staight across the top of the frame then down at a 45 then back straight across the bottom. We measured to a bolt hole or bracket or the straight cut ,just what ever worked out.the fish plates he cut in a diamond shape one on each side of the frame 4plates in all.we streched two brand new semi trucks and made 16-20 foot flatbeds out of them .measure alot then measure some more,then cross square from some ref. points good luck and have fun.
I cut the frame in a "z" step. Cut down half way, then up halfway about 6" over and slice the middle front to back. Then fit it together. You have to do the layout there to figure out how much to remove in the middle. I hope that makes sense. I guess it's the same as the 45 degree thing. I also box in the back 1 1/2 feet either way. And you could fish plate the inside of the outer plate too.
This post is similar to the way it was done on the Spike TV show "Trucks" not saying good or bad, but probably what you were remembering seeing. http://67-72chevytrucks.com/vboard/showthread.php?t=323615
The 45 degree cut idea comes from the woodworkers where joints are glued together and the more surface area for the joint, the stronger the glue joint. Welds are not glue joints...if done correctly. If you are worried about full penetration of your welds then get a pro to do it for you. A properly executed weld will leave NO joint. Some think a weld is like a scab over a crack and the scab/weld is what actually holds the two pieces together like a bridge. Done properly the two parent metals and the filler rod all flow together and become a solid mass when it cools. The old joint no longer exists so there is no underlying crack. Anything else means it was not welded properly. A 45* cut just means more work with no real benefit. Bevel the joint so that the root pass actually burns through the back side of the joint assuring full penetration. Then stringer passes to fill the bevel and restore the complete thickness of the original frame member with no sign of the original cut. The cut area should be just as strong as the rest of the frame.
Heres a pdf to download. I'ts fords method of stretching a truck frame. It's the same method recommended by engineers. All you need to know: http://www.morryde.com/pdfs/Chassis Stretch.pdf http://www.versalifteast.com/articles/truckframes.htm new rails: http://www.viconfab.com/index.htm I searched the HAMB for frame welding, splice and stretch. I found nothing similar so I posted what I found as a new thread here:http://www.jalopyjournal.com/forum/showthread.php?p=4387158#post4387158
Haha, I got tired of posting that article all the time and decided to make it a thread. I used to have a picture of a minitruck build ( i can't find it right now) that had the rear frame made out of a stack of square 2" holy tubing all bolted together with severe optimism. I have yet to hear "how many nails should I use when splicing my frame" but I did see a minivan towing a utility trailer pass me one day. The "trailer" was made out of lumber and was nailed together including the tongue. It had a 16 or 20 horse riding lawn mower and yard supplies on it (not tied down) and no lights. I backed of the throttle hastily. the wood was grey and I saw air between the members every bad bump
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